================================================================== BUG: KASAN: use-after-free in dvb_device_open+0xd4/0x388 drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff0000d3473218 by task syz.3.291/5485 CPU: 1 PID: 5485 Comm: syz.3.291 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call trace: dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 print_address_description+0x88/0x218 mm/kasan/report.c:316 print_report+0x50/0x68 mm/kasan/report.c:420 kasan_report+0xa8/0xfc mm/kasan/report.c:524 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351 dvb_device_open+0xd4/0x388 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x3d4/0x518 fs/char_dev.c:414 do_dentry_open+0x72c/0xf98 fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3634 [inline] path_openat+0x1f8c/0x26bc fs/namei.c:3791 do_filp_open+0x194/0x384 fs/namei.c:3818 do_sys_openat2+0x134/0x3f4 fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x118/0x14c fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Allocated by task 5466: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384 kasan_kmalloc include/linux/kasan.h:211 [inline] kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031 kmalloc include/linux/slab.h:563 [inline] kzalloc include/linux/slab.h:699 [inline] ovl_encode_real_fh+0xd8/0x2ec fs/overlayfs/copy_up.c:350 ovl_verify_set_fh+0x58/0x3a4 fs/overlayfs/namei.c:464 ovl_verify_origin fs/overlayfs/overlayfs.h:545 [inline] ovl_get_indexdir+0x134/0x504 fs/overlayfs/super.c:1559 ovl_fill_super+0x1580/0x2240 fs/overlayfs/super.c:2120 mount_nodev+0x68/0x104 fs/super.c:1489 ovl_mount+0x3c/0x50 fs/overlayfs/super.c:2186 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 do_new_mount+0x228/0x810 fs/namespace.c:3078 path_mount+0x5bc/0xe80 fs/namespace.c:3408 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount fs/namespace.c:3606 [inline] __arm64_sys_mount+0x49c/0x59c fs/namespace.c:3606 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Freed by task 5466: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4c/0x80 mm/kasan/common.c:53 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1729 [inline] slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755 slab_free mm/slub.c:3687 [inline] __kmem_cache_free+0xbc/0x218 mm/slub.c:3700 kfree+0xd0/0x1a8 mm/slab_common.c:988 ovl_verify_set_fh+0x270/0x3a4 fs/overlayfs/namei.c:478 ovl_verify_origin fs/overlayfs/overlayfs.h:545 [inline] ovl_get_indexdir+0x134/0x504 fs/overlayfs/super.c:1559 ovl_fill_super+0x1580/0x2240 fs/overlayfs/super.c:2120 mount_nodev+0x68/0x104 fs/super.c:1489 ovl_mount+0x3c/0x50 fs/overlayfs/super.c:2186 legacy_get_tree+0xd4/0x16c fs/fs_context.c:632 vfs_get_tree+0x90/0x274 fs/super.c:1573 do_new_mount+0x228/0x810 fs/namespace.c:3078 path_mount+0x5bc/0xe80 fs/namespace.c:3408 do_mount fs/namespace.c:3421 [inline] __do_sys_mount fs/namespace.c:3629 [inline] __se_sys_mount fs/namespace.c:3606 [inline] __arm64_sys_mount+0x49c/0x59c fs/namespace.c:3606 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 The buggy address belongs to the object at ffff0000d3473200 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of 256-byte region [ffff0000d3473200, ffff0000d3473300) The buggy address belongs to the physical page: page:000000004cad62a3 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x113472 head:000000004cad62a3 order:1 compound_mapcount:0 compound_pincount:0 flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff) raw: 05ffc00000010200 0000000000000000 dead000000000001 ffff0000c0002480 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d3473100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000d3473180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000d3473200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d3473280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d3473300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Unable to handle kernel paging request at virtual address dfff800000000020 KASAN: null-ptr-deref in range [0x0000000000000100-0x0000000000000107] Mem abort info: ESR = 0x0000000096000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x06: level 2 translation fault Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 [dfff800000000020] address between user and kernel address ranges Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 5485 Comm: syz.3.291 Tainted: G B syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 pstate: 62400005 (nZCv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--) pc : dvb_device_open+0xe0/0x388 drivers/media/dvb-core/dvbdev.c:103 lr : dvb_device_open+0xd4/0x388 drivers/media/dvb-core/dvbdev.c:99 sp : ffff8000215075e0 x29: ffff8000215075e0 x28: ffff0000ca3b9928 x27: dfff800000000000 x26: ffff7000042a0ec8 x25: dfff800000000000 x24: 1fffe0001a68e643 x23: 0000000000000100 x22: ffff0000d3473218 x21: ffff0000d3ab8790 x20: ffff0000ca3b9900 x19: ffff0000d3473200 x18: ffff800011b9bf60 x17: 1fffe00033eaa57e x16: ffff80000804309c x15: 0000000040000000 x14: 0000000000000001 x13: 1ffff00002fc1d6c x12: 0000000000080000 x11: 000000000007ffff x10: ffff80002971f000 x9 : 0000000000000000 x8 : 0000000000000020 x7 : 0000000000000004 x6 : ffff800008257984 x5 : 0000000000000000 x4 : 0000000000000001 x3 : ffff800008193d18 x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000001 Call trace: dvb_device_open+0xe0/0x388 drivers/media/dvb-core/dvbdev.c:103 chrdev_open+0x3d4/0x518 fs/char_dev.c:414 do_dentry_open+0x72c/0xf98 fs/open.c:882 vfs_open+0x7c/0x90 fs/open.c:1015 do_open fs/namei.c:3634 [inline] path_openat+0x1f8c/0x26bc fs/namei.c:3791 do_filp_open+0x194/0x384 fs/namei.c:3818 do_sys_openat2+0x134/0x3f4 fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x118/0x14c fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585 Code: 969dff85 f94002d7 b40009b7 d343fee8 (38796908) ---[ end trace 0000000000000000 ]--- ---------------- Code disassembly (best guess): 0: 969dff85 bl 0xfffffffffa77fe14 4: f94002d7 ldr x23, [x22] 8: b40009b7 cbz x23, 0x13c c: d343fee8 lsr x8, x23, #3 * 10: 38796908 ldrb w8, [x8, x25] <-- trapping instruction